Alternating-current motor.



.Ho. 854,789. PATENTED MAY 28, 1907.-

- L. A. HAWKINS.

ALTERNATING CURRENT MOTOR.

APPLICATION FILED SEPT. 10,.1906.

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APPLIGATIOH 2 SEEETS-SHBBT Unrrnn sTA'rns- PATENT OFFICE.

LAURENCE A. HAWKINS, or SCHENEOTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ALTERNATlNG-CURFIENT MOTOR.

Specification of Letters Patent.

Patented May 28 1907.

Application filed September 10,1906. I Serial No. 333,916.

To all whom it may concern/.-

Be it. known that I, LAURENCE A. HAW- of New York, have invented certainnew and usefuLImprovements in Alternating-Current- Motors, of which thefollowing is a specification.

My invention relates to alternating-current motors, and its object is torovide a acteristics similar to those of a direct-cur- -rent seriesmotor are obtained without the 1 use of a commutator.

The polyphase induction motor possesses, as is'well known, speed-torquecharacteristics similar to those of a direct-current shunt 'motor,thatis, it is a practically constant speed machine. It, consequently, is notadapted for use in applications in which a characteristic similar tothat of a direct-current series motor is desired,that is, a char:

'acteristic with high starting torque, which .falls off When su raduallyas the speed increases. 51 a characteristic has been desired inalternatingecurrent motors, it has been the practice to providethe motorwith a commutator.- Two types of alternating-current commutator motorshave been widely used.

One is the simple seriesmotor, and the other the repulsion motor inwhich the armature is short-circuited on a line at an angle to the Pimary mag etization! teristics without employinga commutaton Commutationin alternating-current machines presents d ificulties not apparent indirect-current machines, and the object of my invention is to obtain thedesiredvcharac- For this purpose I make use of the same generalprinciple involved in the well known re.-

pulsion motor; If all the armature coils of a motor having asingle-phase primary membar are directly short-circuited on themselvesno starting torque is produced, but if by means of a commutator, aportion only of the coils are short-circuited, or ifallthe coils areshort-circuited on a line at an angle to the lineof primarymagnetization, the desired characteristic is obtained. By my invention Iproduce a distortion of the current distribufl tion in the armaturesimilar to that produced the repulsion motor, but instead of em-,ploying a, commutator to secure this result I '-'p' 1 iovide amagneticshunt so arranged that reference'to the accompanying drawings,in

which Figure l is an explanatory diagram; Fig. 2'

shows a side elevation of an alternating-current motor constructed inaccordance with. my invention, and Fig. 3 shows a plan view of the same,partly in cross-section.

In ,Fig. 1, A represents the primary memher," which is preferablystationary and carries the primarywinding B, which is connected to thesingle phase source of supply. C re resents a Gramme-ring member whichis relatively rotatable with respect tothe primary member A. D reresents a flux shunt, which is stationary wit respect to the primarymember A. The Gramme-ring member C carries distributed sets ofring-wound coils, ofwhich two sets E and E are shown .in F' 1, and alsodrum-wound coils F and F, W fch-are connected in series with thering-wound coils E and E so as to form independent closed circuits."Considering the primary flux, which enters member 0 from one of theprimary poles A, it willbe seen that if there were no windings on theGrammering, the greater portion of the fluxwould pass through theGramme-ring member in 0th directionsto the diametrically-oppositepointand thence to the o posite pole A, while a comparatively small portionwould be shunted through the member ID.

As will be hereafter ex lained, the action of the closed circuits on t esecondary member results inforcin the greater part of the;

primary flux throng the member D, so that the path of the primary fluxis as indicated 1 by the heavy dotted line and arrow-heads.-

\Neglecting for the moment the action of the secondary circuits inreducing ,thisdistri' butionof the flux, an considering onlythe TOOeffect of this flux u on the closed circuitformed by the coils E coil F,it will be seenthat the coilsE E act as and the drum-wound secondarywindings for this flu, and since the two coils E E are ,co 'mect'ed sothat their induced electromotive orces are in series,{,-. they force acurrent through the drum woundf coil IF, which produces" a{magnetization at right-angles to the primary magnetization issuing fromthe poles-A. Consequently the current in the coil F co-acts with thecurrent in the primary winding and produces a torque upon the secondarymember C.

It Will be seen that the coil F is substantially parallel to the line ofprimary magnetization, and consequently it is in noninductive relationto the primary flux. In other Words, the ring-Woundcoils E act astransformer coils for producing the induced electromotive force, whilethe coil F acts as a motor coil for producing the motor torque. Thecoils E and F should be displaced from each other, as indicated in Fig.1, so that the coils E may occupy the most favorable position foreiiective transformer action,-that is, a position between the pole A andthe adjacent pole of the member D, while the coil F is in the mosteffective position for motor'action,-that is, substantially atright-angles to the line joining the poles A A. a

It Will further be seen that the current in the closed circuit formed bythe coils E, E and F, and consequently the torque, will be greatest atstarting, since when the member 0 is-at rest there is nocounter-electronictive force due to rotation in its circuit. As themember C begins to revolve, however, the

coil F cuts the primary field, and has induced in it an electromotivetorce which opposes the I electromotive force induced by transformeraction in the coils. E. Rotation has but little effect on theelectromotive forces induced in the coils E E, since while the outersides of these coils are cutting the field be tween the pole A. and themember C the inner sides of these coils are moving in the same directionthrough practically equal field between member {I and the stations-i berD. Consequently the inducer. tromotive for-"e in coil E remains callyconstant, while a counter-elsetrot force due to rotation exists in the tthat the resultant curr nt in the ch cuit formed by these coilsdecreases as the motor speeds u in other words, the speed-torquecteristic' is the same as that inthe comm is above that prae cuited d. ithat they the primary flux through the flux shunt, and if the number ofturns in the coils E E is great with respect to the number of turns inthe coils F, they will still act as though practically short-circuited.

Moreover, by connecting the coils E and F in opposition with respect tothe primary flux passing through them, as shown in Fig. l, the fiuXpassing through the coils E will be in'opposition to the direction ofthe primary flux, and will close itself through the flux shunt D, asindicated by the light dotted lines and arrow-heads. This flux is in thesame direction as the primary flux in the member D and in the portion otthe Granunering occupied by the coils E E; and the amount oi this fluxmultiplied by the number of turns in the coils E E willbe practicallyequal to the primary flux multiplied by the. number of turns in thecoils F. T he'eflect of this flux on the closed circuit formed by coilsE, E, and F, is to increasethe electromotive force induced bytransformer action in coils E, E, and also to produce in these coils acounter-electromotive force due to'ro tation which is in series withthat prodi ced in coil F by cutting the primary field. Thus, 1

the closed circuits, when they reach the position shownby the coils E Eof F g. 1, act, as has been heretofore stated, to divert practically allthe primary flux to the shunting member D. Consequently, this arrangement of magnetic circuits and closed electrical circuits produces aneliective inequality of primary flux distribution in the secondarymember, which results in a motor torque having the characteristics abovedescribed.

A suitable motor construction, in accordance with the principles aboveexplained, is shown in Figs. 2 and 3. In the construction shown in thesefigures, which particularly adapted for bi-polar motors, the motor comprises in eilect two structures, each similar to that showndiagrannnatically in Fig. l. The

' nien'iber comprises two stationary laminated members shown. arracingeach other in a horizontal so as to form two pairs of opposite l Ipoles. winding B. Two laminated Gramme-ring members C are supported froma central spider C, on the shaft C and carry the ringwound coils E andthe drum-wound coils F i i do slots. The stationary flux shunts den theshalt and are ad V on by means oi the worms G en- '8, shown in do nlines in Fig. {TCS oi the membt tion the motor may be adjusted byadjusting the position. of the members D, and the direction ol' rotationof the motor may be reversed by reversing the position of these memberswith respect to the primary poles.

While a bi-polar construction is shown in the drawings, it will beunderstood that my invention is equally applicable to multi-polarmachines.

- Furthermore, the construction sho n is only one of many in which myinvention may be embodied. Accordingly, I do not desire On these polesis placed. the prin'iary .1 The opto limit myself to the particularconstruc ion and arrangement'of parts here shown, but aim in theappendedclaims to cover all modifications which are within the scope of myinvention.

-What I claim as new and desire to secure by Letters-Patent'of theUnited States, is,

' 1. In an alternating-current motor,a pri- .1nary winding, a secondarywinding comprising independent coils relatively rotatable with respectto the primary winding, a mag-. netic circuit arranged to shunt theprimary flux' away from a portion of said coils, and independentcross-magnetizing coils com'iecterh in series with the several secondarycoils.

2.,LIn an 'alternatin -current motor, a primary membenawin ing thereon,a secbndary member relatively rotatable with respect to the primarymember, the magnetic circuit for the primary flux being arranged toproduce unc ual magnetizations in different portions of t e secondarymember, independent coils distributed on the secondary member, andindependent cross-magnetizing coils on the. secondary member connectedin series 7 witlrthe several secondary coils.

3. In an alternating-current motor, a primary winding, a secondarywinding comprisin distributed coils connected to form apluralityofindependent'closed' circuits, a magnetic circuit for saidwindings arranged to p'roducean unequal distribution of the, primaryflux in ,said coils, and cross-magneti'zing coils included in saidclosed circuits.

4. In an alternating-current motor, a primar winding, a relativelyrotatable second win ing; comprising distributed coils connectedfto formindependent closed circuits,

and a-magnetic flux-shunt arranged atv an angle 'to the line ofmagnetization produced by the primary-winding and adapted to form ashunt for the primary flux with respect'to a po'rtion'of' the secondarymember. 5. In an alternating-current motor, a pmshni'it for the primaryflux with respect to .t

por on of the secondary member.

6. inan aiternatiugwurren't motor, a premary member, a winding thereon,a Grammaring secondary member relatively rotatable ,w1th respect to theprimary member, ringwound coils distributed on the secondary member,drum-wound coils connected in series with the ring-wound coils to form aplurality 'of independent closed circuits, and means for producing anunequal. distribution of the primary flux in the Gramme-ring member.

7. In an alternating-current motor, a primary member, a windingthereon,a Grammering secondary member relatively rotatable with respect to theprimarymember, ring- Wound coils distributed on the secondary member,drum-woundcoils connected in series with the ring-wound coils to form aplurality of independent closed circuits, and means for producing anunequal distribution of the primary flux in the Gramme-ring member, thering-wound and drum-wound coils being op ositely-wound with respect tothe primary llX in said Gramme-ring member.

In Witness whereof, I have hereunto set my hand this 8th day ofSeptember, 1906.

LAURENCE A. HAWKINS.

